Antenna structure with coupling network



A ril 21,1959 M. R. sLoP'PY 2,833,664

ANTENNA STRUCTURE WITH COUPLING NETWORK Filed July s, 1953 INVENIOR.

MILTON ROY SLOPPY BY RNLA ("m Qfiarnt United States Patent 2,883,664 ANTENNA STRUCTURE WITH COUPLING NETWORK Milton Roy Sloppy, Syracuse, N.

Application July 3, 1953, Serial No. 365,862 Claims. (Cl. 343-820) This invention relates to antenna structures, and has particular reference to a novel all-directional, self-tuning antenna for the reception of television and radio waves.

In the conventional types of dipole antennas and variations thereof in common use at the present time, the antenna usually has the disadvantage that it is not alldirectional. Thus, energy waves striking the antenna from different directions have different effects on the antenna and therefore on the reception. Briefly stated,

the reason for this is that when the direction of the wave changes there is a variance in the total distance between antenna poles that the wave cuts across. In the case of roof-supported antennas for home television sets, the antenna is usually mounted so that the waves from the local transmitting station strike it in the most advantageous manner, and waves from other stations usually give proper reception. Some home antennas, of course, are rotatably mounted to compensate for this last-mentioned disadvantage but such antennas are expensive to install and maintain, and require continual rotational adjustment to obtain the best reception.

Many home television sets are equipped only with the rabbit ears" or antler type of antenna which is an indoor unit that usually rests on top of the set. This type of antenna, too. must be continually adjusted as to position in order to give the best possible reception as different channels are tuned in. An even greater problem, however, connected with the indoor antenna, and one which sometimes also occurs with roof supported antennas, is that of reflected waves from walls, articles of furniture or other objects. Thus, in actual practice, there may be waves cutting across the antenna from many difierent directions, and this condition may hinder good reception even though the amplitude of the reflected waves is somewhat diminished.

It will be understood that the aforementioned problems connected with stationary antennas will to a large degree he accentuated in the case of antennas mounted upon moving objects such as aircraft, ships or land vehicles where the supporting object itself may frequently change direction.

Accordingly, and in order to overcome many of the difficulties briefly outlined above, it is the primary obiect of the present invention to provide an all or omnidirectional antenna for the reception of television and radio waves wherein waves from any direction, reflected or direct, induce exactly the same electrical eflect upon the antenna and the efiect produced results in superior reception. Because the result produced by energy waves striking the antenna of the invention is substantially the same and is uniformly efficient regardless of the direction of the waves, the antenna is well adapted for use with moving vehicle installations as well as with stationary receivers.

Another very important object of the invention is to provide an all-directional antenna that is also self-tuning in that its tuning coils automatically adjust to the frequency to which its receiver is tuned.

A further important object of the invention is to provide an all-directional, self-tuning antenna for VHF- UHF television and F M radio reception.

Still another important object of the invention is to provide an all-directional, self-tuning antenna that is efficient and practical for a wide range of applications and at the same time is relatively simple and economical to produce.

A more specific object of the invention is to provide an all-directional antenna having a novel pole construction and arrangement.

A further specific object of the invention is to provide an all-directional, self-tuning antenna having a greatly improved tuning coil construction.

Other objects and advantages will become apparent from the following detailed description read in connection with the accompanying drawings wherein like reference numbers designate corresponding parts in all the views.

Figure 1 is a plan view of an all-directional, self-tuning antenna embodying the invention, with the top covering member removed.

Figure 2 is a reduced plan view of the antenna of Figure 1 with the top covering member secured in position.

Figure 3 is an enlarged section through the antenna of Figure 2, taken along line 33 thereof.

Figure 4 is a section through a portion of the antenna of Figure 1, taken along line 44 thereof.

Figure 5 is a section through another portion of the antenna of Figure 1, taken along line 55 thereof.

Having reference now to the drawings which illustrate a typical embodiment of the invention for the purpose of disclosure, 10 generally indicates the antenna having a base portion or member 11. Base portion 11 is formed of a substantially fiat, non-conducting material which is shown in the drawings as a circular piece of corrugated cardboard although other shapes and materials can be used equally well. Positioned on the base 11 are a pair of pole portions or elements 12, 14 which are in the form of segments of a circle, the pole portions being spaced apart as shown with their chord sides 15, 17, respectively, being in confronting parallel relation. In the illustrated embodiment, the poles 12, 14 are formed from metal foil and are adhesively secured to a separate base member. It will be understood, however, that the poles could be in the form of a metal film sprayed or painted directly on the base with the aid of properly shaped templates.

The segments forming the poles 12, 14 are identical and are formed so that the width of each segment at its widest point is equal to one-third the length of its chord or chord side. Now if the poles 12, 14 are arranged so that their chords 15, 17 are perpendicular to a diameter 18'of the circular base 11 and intersect the diameter at the mid-points of the chords, the widest points of the pole segments will be at points A and B, respectively, and the portion 20 of the diameter between chord 15 and point A will be equal to one-third the length of chord 15 while portion 21 of the diameter between chord 17 and point B will be equal to one-third the length of chord 17. In addition, the poles 12, 14 are positioned on the base 11 so that the distance between them, or between their chords 15, 17, is equal to one-third the length of a chord. It will be seen, therefore, that the total distance between points A and B on poles 12 and 14, respectively, is equal to the length of the chords.

In the present invention it has been found that if the length of the chords is Va meter or a multiple or fraction of meter, and the pole construction and arrangement above-described is followed, the antenna will enable exceptionally clear reception and will be truly all or omnidirectional since energy waves striking the antenna will always cut across both poles for substantially the same total distance regardless of the direction of origin of the waves. For example, if the chords 15, 17 are Ms meter in 3 length, the distance between points A and B will also be meter and it will be seen that any waves moving from top to bottom in Figure 1 or vice versa, or from left to right or vice versa, will cut across both poles for a total distance of /3 meter. Waves moving across the antenna from any other direction will cut across both poles for a total distance of slightly more than 6 meter but the additional distance travelled is so small in comparison to the total distance the effect upon the antenna is the same, and for all practical purposes it may be considered that the total distance across both poles in any direction is /3 meter.

Coacting with poles 12 and 14 are special tuning coils 22, 24, respectively. It is desirable that the tuning coils be of a fiat or pancake type in the present invention so that the antenna structure can be in a fiat, compact form. It is very important, however, that the inductance and impedance of the coils be closely controlled because, as is now well understood by those working in the art, too much induction between the turns of tuning coils for television receivers, for example, may fog the image on the screen. In order to form flat coils having controlled inductance and impedance, the invention contemplates forming coils 22, 24 from a sheet of metal foil similar to the pole material, which foil is backed with a nonelastic film or sheet of plastic material of controlled thick? ness. The foil and plastic backing are rolled into a tight cylindrical coil, and the fiat coils 22, 24 are then sliced from the cylinder by suitable cutting means. Thus, the coils 22, 24 are preferably formed of rectangular foil conductors rather than the conventional cylindrical wire conductors.

A portion of each coil 22, 24 is unwound to provide straight conductors or leads 25, 27, respectively, which coact with the leads 28, 30 of a twin lead transmission line 31 which is secured at one end to the base 11 as by a staple 32. Transmission line 31 may be a conventional 300 ohm lead-in line, the leads of which are bent outwardly at right angles to the longitudinal axis of the line, as shown. The coil 22 is electrically connected with pole 12 through contact made by the inner end 34 of the coil as may be best seen in Figure 4. The conductor 25 of coil 22 is likewise electrically connected to the lead 28 of the transmission line whose insulating covering is cut away at the contact point as shown in Figure 1. Since the conductor 25 is too fragile to solder, it is secured to the bared portion of lead 28 by means of a connector 35 of creped foil in the shape of an annulus, the conductor and lead being passed through the center opening of the annulus. The coil 24 is capacitively and inductively connected with pole 14 andis therefore insulated therefrom by means of a thin sheet of insulating material 37 as may be best seen in Figure 5. The conductor 27 of coil 24 is likewise capacitively and inductively connected with the lead 30 of the transmission line since the insulation covering the lead is not cut away at the point of contact as in the case of conductor 25 and lead 28.

The antenna has a broad-banded property because the coil will adjust to, or put itself in resonance with, the frequency of the channel or station that the receiver is tuned for by using more or less of its turns for the proper capacitance or inductance. The reason that conductor 27 is capacitively or inductively connected with lead 30 is to permit UHF waves to be received. Since there is no electrical connection at this point on the system, UHF waves can resonate employing transmission line leads 28, 30 as poles. The electrical effect of such a connection is the same as if a condenser were used at this point but the need for the condenser is eliminated by the method of connection described.

The antenna is provided with a cover member 38 corresponding in shape to the shape of base 11 and being formed of similar fiat, non-conducting material. The cover member 38 is positioned over the poles, coils and conductors above-described, and secured to the base as by binding tape 40, Figures 2 and 3, extending about the peripheries I of the members and overlying their outer marginal edges. A suitable slot or notch (not shown) may be cut in the tape to permit the passage of transmission line 31 therethrough. The assembled antenna will be in the form of a substantially flat, circular package as indicated in Figure 2, and can be conveniently stored within the receiver or in any other convenient place, occupying a of space. In the case of home receivers, the antenna can if desired be covered with attractive designs or fabrics and used for decorative purposes.

A specific example of an antenna of the type just disclosed, which has proved to be unusually effective in enabling superior reception, will now be briefly described. The base and cover members are identical circular pieces of corrugated cardboard. The poles are formed from .007 inch sheets of aluminum foil with chords Vs meter or 13.125 inches in length. These poles are arranged on the base as above described and are adhesively secured thereto. The tuning coils are also formed from sheets of aluminum foil backed by a non-elastic sheet of plastic so that the foil can not be broken as by stretching. Each coil comprises 36 turns of the rectangular foil conductor, and the total length of foil in the coil and its lead to the transmission line is 1% meters. The transmission line is a conventional 300 ohm lead-in Wire. The right hand coil is separated from its pole by an .003 inch sheet of insulating material. The cover member is positioned over the poles, coils and conductors as previously described and secured to the base member by a fabric or plastic tape so that the operating parts of the antenna are completely enclosed.

From the foregoing description it will be apparent that the invention provides a novel all-directional, self-tuning antenna for the reception of television and radio waves. The invention can, of course, be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The embodiment disclosed is therefore to be considered in all respects as illustrative rather than restrictive, the scope of the invention being indicated by the appended claims.

What I claim is:

1. In an all-directional antenna for television and radio reception: a flat non-conducting base member; a pair of identical metal foil pole elements in the form of segments of a circle mounted on said base member, each of said elements having a width at its widest point equal to one-third the length of its chord side, said elements being arranged on said base member with their chord sides in confronting parallel relation and spaced apart a distance equal to one-third the length of a chord side.

2. An all-directional, self-tuning antenna for television or radio reception comprising: a flat non-conducting base member; a pair of identical metal foil pole elements in the form of segments of a circle mounted in spaced re.- lation on said base member with their chord sides confronting and parallel to each other, the length of the chord side of each pole element being three times the width of the element at its widest point and also three times the distance between said elements; a first flat conducting coil electrically connected with one of said pole elements; a second flat conducting ooil capacitively connected with the other of said pole elements; a twin lead transmission line secured at one end to said base member; a first electrical conductor electrically connecting said first coil with one of the transmission line leads; and a second electrical conductor capacitively connecting Taid second coil with the other of the transmission line eads.

3. An antenna as defined in claim 2 wherein said coils are formed of metal foil backed by non-conducting plastic.

4. In an antenna structure: a non-conducting base member; a pair of spaced apart sheet material pole elements supported by said base member, said pole elements being in the form of segments of a circle with their chord sides in confronting parallel relation, the width of each pole element being equal at its widest point to one-third the length of its chord side and the distance between said elements being likewise equal to one-third the length of a chord side; a twin lead transmission line; and a pair of electrical conductors respectively extending between said pole elements and the leads of said transmission line.

5. In a portable antenna structure: a non-conducting base portion; a pair of identical pole portions in the form of segments of a circle supported by said base portion, the width of each of said pole portions at its widest point being equal to one-third the length of its chord side, said pole portions being spaced apart with their chord sides in confronting parallel relation, the distance between said pole portions also being equal to one-third the length of a chord side; a first electrical conductor having an electrical connection with one of said pole portions; a second electrical conductor capacitively and inductively connected with the other of said poles; and

a twin lead transmission line, the leads of which are respectively electrically, and capacitively and inductively connected with said first and second conductors.

References Cited in the file of this patent UNITED STATES PATENTS 1,158,124 Fessenden Oct. 26, 1915 1,228,647 Butcher June 5, 1917 1,563,731 Ducas Dec. 1, 1925 1,765,438 Meissner June 24, 1930 2,551,664 Galper May 8, 1951 2,555,857 Nelson et a1. June 5, 1951 2,632,849 Fyler Mar. 24, 1953 2,650,304 Schlesinger Aug. 25, 1953 2,657,312 Saranga Oct. 27, 1953 OTHER REFERENCES Kraus: Antennas, 1st ed. (1950), McGraw-Hill, pages 444-447. 

